This and a companion project (Z01 HD001123) investigate auditory communication in primates. The overall goal of these studies is to provide a comprehensive understanding of primate auditory communication in terms of development, neural mechanisms, endocrine factors, and social context. Two species, the squirrel monkey and the common marmoset, have been the main subjects of study, with additional data collected from other species where appropriate. The present project studies primate communication from a bioacoustic and ethological perspective, focusing on the detailed acoustic structure of vocalizations produced in natural settings, and the relationship of structural differences to differences in age, gender, experience and response selectivity, as well as the broader factors of social context and genetic background. Prior work in this project has determined that there is considerable individual variation in the detailed acoustic structure of infant cries, which is stable over at least the first 3 months of life. A detailed analysis of the infant cries of prosimian primates was completed last year. Prosimians are of interest because of the long period of separation from other primate groups evolutionarily, and the fact that several prosimians are active nocturnally. It was found that the infant cries of bushbabies are click-like in structure, very different from the tonal cries of simian primates. Furthermore, the cries of several diurnal lemurs differ in some respects from the tonal cries of simian primates. This variety of cry acoustics suggests that prosimians, being the earliest primate line, may have experimented with different types of cries. It would be of interest to investigate the laryngeal structure of these prosimians and compare them with the larynges of simian primates, as this may give important clues on the differences in cry production across the primates as a whole. A new initiative this year, in collaboration with the Evolutionary Biology Program at Cornell, has begun to explore the relationship between vocal behavior and phylogeny, using bioacoustic and genetic analyses of the individual species in vertebrate groups. The initial effort has focused on a group of songbirds, the warblers (family Parulidae). A DNA analysis of phylogenetic relationships developed at Cornell is now available, and provides the basis for examining the relationship between phylogenetic affinities and vocal characteristics. As songbirds, warblers have well-defined songs, which provides a particularly robust phenotypic database for comparison. In addition, the Macaulay Library at the Cornell Laboratory of Ornithology has the largest collection of digital recordings of natural sounds in the world. Access to the Library has made it possible to download and begin analysis of the songs of nearly 100 species of warblers, all of which have DNA samples that have been analyzed.